I. FIELD OF THE INVENTION
The present invention relates generally to debarking machines used in the timber processing industry that have a rotor that engages and feeds logs through an orifice surrounded by a plurality of arcuate debarking tools. More particularly, the present invention relates to debarking tools for ring-rotor debarking machines. Relevant prior art debarking tools and machines may be found in United States Patent Class 144 and the many subclasses listed thereunder.
II. DESCRIPTION OF THE PRIOR ART
As will be recognized by those skilled in the art, ring rotor debarking machines comprise a rotor having a plurality of arcuate, radially spaced apart debarkers disposed upon the circumference. The debarking tools arc inwardly towards the central opening of the rotor, and forcibly contact logs being drawn through the apparatus. The debarking tools extend radially inwardly from their attachment at the exterior of the rotor. The tools distally mount cutting edges that are resiliently disposed adjacent the axis of rotation of the rotor.
When the rotor is rotated and a log enters the rotor inlet, the tools vigorously engage the log. Initial engagement forces the spring-loaded debarking tools to climb the log surface, opening outwardly to circumscribe the log. Radial movement of the tools disposes their cutting edges upon the exterior surface of the log where they begin debarking the log. When the log exits the rotor outlet, normal forces biasing the tools radially inwardly force them to rapidly close inwardly.
The prior art discloses several debarking tools that work in the manner discussed hereinabove. U.S. Pat. No. 4,280,541, issued Jul. 28, 1981, to Reimler et. al., teaches an invention that climbs up logs with irregular ends. U.S. Pat. No. 3,973,607, issued Aug. 10, 1976 to Jonsson, discloses a debarking tool that has an integrally formed arm that is chute shaped.
A design patent of interest is U.S. Pat. No. Des. 276,161, issued Oct. 30, 1984, to Valo that shows a debarking tool that has a curved leading edge. U.S. Pat. No. 2,911,020, issued Nov. 3, 1959, to Wennberg, shows a debarking tool that has an elongated arcuate bark deflecting wing on the leading edge of the tool. U.S. Pat. No. 4,653,559, issued Mar. 31, 1987, to Ackerman discloses a forwardly-projecting debarking tool debarker arm that is located ahead of the leading face of the barker arm.
Several other inventions of general relevance are U.S. Pat. Nos. 4,657,056; 4,506,713; 4,516,513; 4,653,561; 4,852,622; 5,193,597 and 5,263,522. These inventions deal with other aspects of the debarking machine.
However, the prior art fails to accommodate the stress resulting from the rapid inward movement the debarking tools undergo when the log exits the outlet. This movement often causes breakage or weakening of the tools when they contract too rapidly. Therefore, it is desirable to provide a debarking tool that climbs down the log in the same manner as the prior art tools climb up the log. Another problem with the prior art is that logs sometimes back up into the exit end of the rotary head. Unless provisions are made for this phenomena, damage can occur.